better question would be... how do you FIND a momentus or marlix because i've been wandering around the wild for days trying to find one and so far havent

be on a less populated server, be in wastelands (they spawn more commonly there ive found), be in grasslands/desert, move alot in said biome jumping seems to help (i think because it resets the block you land on)

be on a less populated server, be in wastelands (they spawn more commonly there ive found), be in grasslands/desert, move alot in said biome jumping seems to help (i think because it resets the block you land on)